TBM Thrust on Fibre Reinforced Concrete Precast Segment Simulation

Fibre reinforced concrete (FRC) is gaining acceptance as a structural material for casting precast segments as this has proven to lead to various advantages respect to the traditional reinforced concrete, especially for improving the crack control during transient loading situations. Concentrated loads induced during the excavation stage by Tunnel Boring Machines (TBMs) is still a matter of discussion into the tunnelling construction field, this having a strong impact from both technical and economic perspectives. In this regard, although specific codes and guidelines have been published and intense research has been carried out, this pointing out the benefits of using FRC as partial or total substitution of conventional reinforcement; however, there is still not a thorough research on the effectiveness of the FRC strength class (as defined into the fib Model Code 2010) to control crack widths in tunnel linings during the TBM thrust phase. To this end, the objective of this research contribution consists in carrying out a parametric analysis, considering different FRC strength classes (including hybrid reinforcements), related with the crack patterns due to the TBM-thrust on FRC segments. This was performed by means of a comprehensive non-linear finite element (FE) numerical simulation. The results derived from this research are meant to be useful for those stakeholders involved in the design of precast tunnel linings.